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Sep 21, 2013
09/13

by
Zhengchun Zhou; Aixian Zhang; Cunsheng Ding; Maosheng Xiong

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Cyclic codes are a subclass of linear codes and have wide applications in consumer electronics, data storage systems, and communication systems due to their efficient encoding and decoding algorithms. Cyclic codes with many zeros and their dual codes have been a subject of study for many years. However, their weight distributions are known only for a very small number of cases. In general the calculation of the weight distribution of cyclic codes is heavily based on the evaluation of some...

Source: http://arxiv.org/abs/1301.4824v2

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Sep 21, 2013
09/13

by
Abhinav Saket; S. R. Hassan; R. Shankar

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We analyse a spin-1/2 chain with two-spin interactions which shown to exactly solvable by Lieb, Schultz and Mattis. We show that the model can be viewed as a generalised Kitaev model that is analytically solvable for all defect sectors. We present an alternate proof that the defect free sector is the ground state, which is valid for a larger parameter range. We show that the defect sectors have degenerate ground states corresponding to unpaired Majorana fermion modes and that the degeneracy is...

Source: http://arxiv.org/abs/1301.5786v1

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Sep 21, 2013
09/13

by
Vladislav Bukshtynov; Bartosz Protas

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We develop an optimization-based approach to the problem of reconstructing temperature-dependent material properties in complex thermo-fluid systems described by the equations for the conservation of mass, momentum and energy. Our goal is to estimate the temperature dependence of the viscosity coefficient in the momentum equation based on some noisy temperature measurements, where the temperature is governed by a separate energy equation. We show that an elegant and computationally efficient...

Source: http://arxiv.org/abs/1301.5922v1

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Sep 21, 2013
09/13

by
L. Feher; P. A. Horvathy

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The Kepler-type dynamical symmetries of the Kaluza-Klein monopole are reviewed. At the classical level, the conservation of the angular momentum and of a Runge-Lenz vector imply that the trajectories are conic sections. The o(4) algebra allows us to calculate the bound-state spectrum, and the o(3,1) algebra yields the scattering matrix. The symmetry algebra extends to o(4,2).

Source: http://arxiv.org/abs/0902.4600v2

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Sep 18, 2013
09/13

by
Angela Zalucha; Timothy Michaels

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We present a 3D general circulation model of Pluto and Triton's atmospheres, which uses radiative-conductive-convective forcing. In both the Pluto and Triton models, an easterly (prograde) jet is present at the equator with a maximum magnitude of 10-12 m/s and 4 m/s, respectively. Neither atmosphere shows any significant overturning circulation in the meridional and vertical directions. Rather, it is horizontal motions (mean circulation and transient waves) that transport heat meridionally at a...

Source: http://arxiv.org/abs/1211.0009v2

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Sep 21, 2013
09/13

by
A. Kh. Khudoyberdiyev; B. A. Omirov

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In the present paper we obtain the list of algebras, up to isomorphism, such that closure of any complex finite-dimensional algebra contains one of the algebra of the given list.

Source: http://arxiv.org/abs/1301.5777v1

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Sep 18, 2013
09/13

by
Donu Arapura; Parsa Bakhtary; Jarosław Włodarczyk

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In this paper, we extract natural invariants of a singularity by using the Deligne weight filtration on the cohomology of an exceptional fibre of a resolution, and also on the intersection cohomology of the link. Our primary goal is to study and give natural bounds on the weights in terms of direct images of differential forms. These bounds can be made explicit for various standard classes such as rational, isolated normal Cohen-Macaulay and toroidal singularities, and lead to strong...

Source: http://arxiv.org/abs/1102.4370v4

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Sep 23, 2013
09/13

by
Yuri B. Suris

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Recently, Lobb and Nijhoff initiated the study of variational (Lagrangian) structure of discrete integrable systems from the perspective of multi-dimensional consistency. In the present work, we follow this line of research and develop a Lagrangian theory of integrable one-dimensional systems. We give a complete solution of the following problem: one looks for a function of several variables (interpreted as multi-time) which delivers critical points to the action functionals obtained by...

Source: http://arxiv.org/abs/1212.3314v2

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Jul 20, 2013
07/13

by
ATLAS Collaboration

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A measurement of spin correlation in ttbar production is reported using data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 2.1 fb^-1. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. The difference in azimuthal angle between the two charged leptons in the laboratory frame is used to extract the correlation between the top and antitop quark spins. In the helicity basis the measured...

Source: http://arxiv.org/abs/1203.4081v3

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Sep 18, 2013
09/13

by
Pierre Sacré; Rodolphe Sepulchre

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Sensitivity analysis is a classical and fundamental tool to evaluate the role of a given parameter in a given system characteristic. Because the phase response curve is a fundamental input--output characteristic of oscillators, we developed a sensitivity analysis for oscillator models in the space of phase response curves. The proposed tool can be applied to high-dimensional oscillator models without facing the curse of dimensionality obstacle associated with numerical exploration of the...

Source: http://arxiv.org/abs/1211.7317v2

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Sep 18, 2013
09/13

by
Amrit Poudel; Luke Langsjoen; Maxim Vavilov; Robert Joynt

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We present our study of decoherence in charge (spin) qubits due to evanescent-wave Johnson noise (EWJN) in a laterally coupled double quantum dot (single quantum dot). The high density of evanescent modes in the vicinity of metallic gates causes energy relaxation and a loss of phase coherence of electrons trapped in quantum dots. We derive expressions for the resultant energy relaxation rates of charge and spin qubits in a variety of dot geometries, and EWJN is shown to be a dominant source of...

Source: http://arxiv.org/abs/1211.3983v3

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Sep 21, 2013
09/13

by
Francesco Malaspina; Fabio Nicola

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We consider a locally integrable real-analytic structure, and we investigate the local solvability in the category of Gevrey functions and ultradistributions of the complex d' naturally induced by the de Rham complex. We prove that the so-called condition Y(q) on the signature of the Levi form, for local solvability of d' u=f, is still necessary even if we take f in the classes of Gevrey functions and look for solutions u in the corresponding spaces of ultradistributions.

Source: http://arxiv.org/abs/1301.5736v1

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Sep 21, 2013
09/13

by
Emanuele Nardini; Junfeng Wang; Giuseppina Fabbiano; Martin Elvis; Silvia Pellegrini; Guido Risaliti; Margarita Karovska; Andreas Zezas

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We report on a recent ~150-ks long Chandra observation of the ultraluminous infrared galaxy merger NGC 6240, which allows a detailed investigation of the diffuse galactic halo. Extended soft X-ray emission is detected at the 3-sigma confidence level over a diamond-shaped region with projected physical size of ~110x80 kpc, and a single-component thermal model provides a reasonably good fit to the observed X-ray spectrum. The hot gas has a temperature of ~7.5 million K, an estimated density of...

Source: http://arxiv.org/abs/1301.5907v1

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Sep 18, 2013
09/13

by
R. Aloisio

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We will review the main physical aspects of Ultra High Energy Cosmic Rays. We will discuss in particular their propagation through astrophysical backgrounds, focusing on the latest experimental observations of HiRes, Telescope Array and Auger. We will also review the issue of the transition between galactic and extra-galactic cosmic rays.

Source: http://arxiv.org/abs/1211.2004v2

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Sep 21, 2013
09/13

by
Yousef Estaremi

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In this paper some results of [7] are developed for subadditive separating maps between C(X;E) and C(Y;E), such that E is a unital Banach algebra.

Source: http://arxiv.org/abs/1301.5727v1

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Sep 21, 2013
09/13

by
Maximilian Stahlhofen

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We report on a recent determination of the bottom quark mass from nonrelativistic (large-n) Upsilon sum rules with renormalization group improvement (RGI) at next-to-next-to-leading logarithmic (NNLL) order. The comparison to previous fixed-order analyses shows that the RGI computed in the vNRQCD framework leads to a substantial stabilization of the theoretical sum rule moments with respect to scale variations. A single moment fit (n=10) to the available experimental data yields M_b^{1S}=4.755...

Source: http://arxiv.org/abs/1301.3493v3

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Sep 21, 2013
09/13

by
Benoit Laslier; Jean-Francois Laslier

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The paper deals with the problem of finding the best alternatives on the basis of pairwise comparisons when these comparisons need not be transitive. In this setting, we study a reinforcement urn model. We prove convergence to the optimal solution when reinforcement of a winning alternative occurs each time after considering three random alternatives. The simpler process, which reinforces the winner of a random pair does not always converges: it may cycle.

Source: http://arxiv.org/abs/1301.5734v1

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Sep 21, 2013
09/13

by
N. J. O. Silva; S. Saisho; M. Mito; A. Millán; F. Palacio; A. Cabot; Òscar Iglesias; A. Labarta

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We report a study on the pressure response of the anisotropy energy of hollow and solid maghemite nanoparticles. The differences between the maghemite samples are understood in terms of size, magnetic anisotropy and shape of the particles. In particular, the differences between hollow and solid samples are due to the different shape of the nanoparticles and by comparing both pressure responses it is possible to conclude that the shell has a larger pressure response when compared to the core.

Source: http://arxiv.org/abs/1301.5708v1

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Sep 21, 2013
09/13

by
E. C. Behrman; R. E. F. Bonde; J. E. Steck; J. F. Behrman

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Entanglement of a quantum system depends upon relative phase in complicated ways, which no single measurement can reflect. Because of this, entanglement witnesses are necessarily limited in applicability and/or utility. We propose here a solution to the problem using quantum neural networks. A quantum system contains the information of its entanglement; thus, if we are clever, we can extract that information efficiently. As proof of concept, we show how this can be done for the case of pure...

Source: http://arxiv.org/abs/1301.6107v1

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Sep 21, 2013
09/13

by
Laure Sansonnet; Christine Malot

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This paper proposes a model of interactions between two point processes, ruled by a reproduction function h, which is considered as the intensity of a Poisson process. In particular, we focus on the context of neurosciences to detect possible interactions in the cerebral activity associated with two neurons. To provide a mathematical answer to this specific problem of neurobiologists, we address so the question of testing the nullity of the intensity h. We construct a multiple testing procedure...

Source: http://arxiv.org/abs/1301.5802v1

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Sep 20, 2013
09/13

by
CMS Collaboration

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Results from the first study of isolated-photon + jet correlations in relativistic heavy ion collisions are reported. The analysis uses data from PbPb collisions at a centre-of-mass energy of 2.76 TeV per nucleon pair corresponding to an integrated luminosity of 150 inverse microbarns recorded by the CMS experiment at the LHC. For events containing an isolated photon with transverse momentum pt(gamma) > 60 GeV and an associated jet with pt(Jet) > 30 GeV, the photon + jet pt imbalance is...

Source: http://arxiv.org/abs/1205.0206v2

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Sep 20, 2013
09/13

by
Pierre-François Loos

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We show that the expression of the high-density (i.e small-$r_s$) correlation energy per electron for the one-dimensional uniform electron gas can be obtained by conventional perturbation theory and is of the form $\Ec(r_s) = -\pi^2/360 + 0.00845 r_s + ...$, where $r_s$ is the average radius of an electron. Combining these new results with the low-density correlation energy expansion, we propose a local-density approximation correlation functional, which deviates by a maximum of 0.1...

Source: http://arxiv.org/abs/1207.6849v3

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Sep 22, 2013
09/13

by
I. Antoniadis; D. M. Ghilencea

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For a 4D N=1 supersymmetric model with a low SUSY breaking scale (f) and general Kahler potential K(Phi^i,Phi_j^*) and superpotential W(Phi^i) we study, in an effective theory approach, the relation of the goldstino superfield to the (Ferrara-Zumino) superconformal symmetry breaking chiral superfield X. In the presence of more sources of supersymmetry breaking, we verify the conjecture that the goldstino superfield is the (infrared) limit of X for zero-momentum and Lambda->\infty. (Lambda is...

Source: http://arxiv.org/abs/1210.8336v2

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Sep 18, 2013
09/13

by
Jonathan Meair; Philippe Jacquod

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We construct a scattering theory of weakly nonlinear thermoelectric transport through sub-micron scale conductors. The theory incorporates the leading nonlinear contributions in temperature and voltage biases to the charge and heat currents. Because of the finite capacitances of sub-micron scale conducting circuits, fundamental conservation laws such as gauge invariance and current conservation require special care to be preserved. We do this by extending the approach of Christen and...

Source: http://arxiv.org/abs/1211.5583v2

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Sep 21, 2013
09/13

by
Wenlin Gong; Chengqiang Zhao; Jia Jiao; Enrong Li; Mingliang Chen; Hui Wang; Wendong Xu; Shensheng Han

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Compared with two-dimensional imaging, three-dimensional imaging is much more advantageous to catch the characteristic information of the target for remote sensing. We report a range-resolving ghost imaging ladar system together with the experimental demonstration of three-dimensional remote sensing with a large field of view. The experiments show that, by measuring the correlation function of intensity fluctuations between two light fields, a three-dimensional map at about 1.0 km range with 25...

Source: http://arxiv.org/abs/1301.5767v1

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Sep 21, 2013
09/13

by
Yuji Terashima; Masahito Yamazaki

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We conjecture that a new class of 3d N=2 theories are associated with a quiver Q and a mutation sequence m on it. We define the cluster partition function from the pair (Q, m), and this partition function coincides with the S^3_b partition function of the associated 3d N=2 theory T[(Q,m)]. Our formalism includes the case where 3d N=2 theories arise from the compactification of the 6d (2,0) A_{N-1} theory on a large class of 3-manifolds M, including complements of arbitrary links in S^3. In this...

Source: http://arxiv.org/abs/1301.5902v1

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Sep 21, 2013
09/13

by
Shu-Hui Luo; An-Min Wang

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We present the generalized version of Wang's protocol[A.M.Wang, Phys.Rev.A 74,032317 (2006)] for the remote implementation(sometimes referred to as quantum remote control) of partially unknown quantum operations. The protocol only requires no more than half of the entanglements used in Bidirectional Quantum State Teleportation. We also propose a protocol for another form of quantum remote control. It can remotely implement a unitary operation which is a combination of the projective...

Source: http://arxiv.org/abs/1301.5866v1

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Sep 23, 2013
09/13

by
Stephen Pankavich; Petronela Radu

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We consider semilinear evolution equations of the form $a(t)\partial_{tt}u + b(t) \partial_t u + Lu = f(x,u)$ and $b(t) \partial_t u + Lu = f(x,u),$ with possibly unbounded $a(t)$ and possibly sign-changing damping coefficient $b(t)$, and determine precise conditions for which linear instability of the steady state solutions implies nonlinear instability. More specifically, we prove that linear instability with an eigenfunction of fixed sign gives rise to nonlinear instability by either...

Source: http://arxiv.org/abs/1110.6240v3

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Sep 21, 2013
09/13

by
James Dover; Murad Özaydın

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For Gamma a finite, connected metric graph, we consider the space of configurations of n points in Gamma with a restraint parameter r dictating the minimum distance allowed between each pair of points. These restricted configuration spaces come up naturally in topological robotics. In this paper, we study the homotopy, homeomorphism, and isotopy types of these spaces over the space of parameters r and provide a polynomial upper bound (in the number of edges of Gamma) for the number of isotopy...

Source: http://arxiv.org/abs/1301.5693v1

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Sep 21, 2013
09/13

by
Leslie Ann Goldberg; Paul W. Goldberg; Piotr Krysta; Carmine Ventre

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An extensive literature in economics and social science addresses contests, in which players compete to outperform each other on some measurable criterion, often referred to as a player's score, or output. Players incur costs that are an increasing function of score, but receive prizes for obtaining higher score than their competitors. In this paper we study finite games that are discretized contests, and the problems of computing exact and approximate Nash equilibria. Our motivation is the...

Source: http://arxiv.org/abs/1301.5844v1

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Sep 21, 2013
09/13

by
Edgar Enochs; Sergio Estrada; Alina Iacob

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We give a sufficient condition for the class of Gorenstein injective modules be precovering: if $R$ is right noetherian and if the class of Gorenstein injective modules, $\mathcal{GI}$, is closed under filtrations, then $\mathcal{GI}$ is precovering in $R-Mod$. The converse is also true when we assume that $\mathcal{GI}$ is covering. We extend our results to the category of complexes. We prove that if the class of Gorenstein injective modules is closed under filtrations then the class of...

Source: http://arxiv.org/abs/1301.5694v1

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Sep 18, 2013
09/13

by
Norio Iwase

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Jim Stasheff gave two apparently distinct definitions of an $A_{m}$ form, $m \leq \infty$ in [15,16]. It is also claimed that the two definitions are equivalent in [15,16], while it is not apparently clear for us. That is why we are trying to clarify related things and to show that the claim is actually true under a `loop-like' hypothesis in this paper. Along with these two definitions, we must construct Associahedra and Multiplihedra as convex polytopes with piecewise-linearly decomposed faces...

Source: http://arxiv.org/abs/1211.5741v7

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Sep 21, 2013
09/13

by
S. K. Singh; S. Mahapatro; R. N. Mishra

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We study the extremely neutron-rich nuclei for $Z = 17 - 23$, $37 - 40$ and $60 - 64$ regions of the periodic table by using axially deformed relativistic mean field formalism with NL3* parametrization. Based on the analysis of binding energy, two neutron separation energy, quadrupole deformation and root mean square radii, we emphasized the speciality of these considered regions which are recently predicted islands of inversion.

Source: http://arxiv.org/abs/1301.5807v1

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Sep 21, 2013
09/13

by
Jacek C. Wojdeł; Patrick Hermet; Mathias P. Ljungberg; Philippe Ghosez; Jorge Íñiguez

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We present a scheme to construct model potentials, with parameters computed from first principles, for large-scale lattice-dynamical simulations of materials. Our method mimics the traditional solid-state approach to the investigation of vibrational spectra, i.e., we start from a suitably chosen reference configuration of the material and describe its energy as a function of arbitrary atomic distortions by means of a Taylor series. Such a form of the potential-energy surface is completely...

Source: http://arxiv.org/abs/1301.5731v1

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Sep 21, 2013
09/13

by
Federico Ronchetti

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The study of two body deuteron photo-disintegration is ideal for investigating the transition region from meson exchange to the Quantum Chromo Dynamics (QCD) regime because of its simplicity and amenability to calculation. In the past years, the theoretical efforts have been focused in two different directions: extending at higher energies the models based on meson exchange, and improving the models inspired by QCD principles to extrapolate their predictions at lower energies, in order to find...

Source: http://arxiv.org/abs/1301.5886v1

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Sep 21, 2013
09/13

by
C. González-Santander; P. A. Orellana; F. Domínguez-Adame

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We report the formation of bound states in the continuum driven by AC fields. This system consists of a quantum ring connected to two leads. An AC side-gate voltage controls the interference pattern of the electrons passing through the system. We model the system by two sites in parallel connected to two semi-infinite lattices. The energy of these sites change harmonically with time. We obtain the transmission probability and the local density of states at the ring sites as a function of the...

Source: http://arxiv.org/abs/1301.5776v1

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Sep 21, 2013
09/13

by
Michael Klaiber; Enderalp Yakaboylu; Karen Z. Hatsagortsyan

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We develop a relativistic Coulomb-corrected strong field approximation (SFA) for the investigation of spin effects at above-threshold ionization in relativistically strong laser fields with highly charged hydrogen-like ions. The Coulomb-corrected SFA is based on the relativistic eikonal-Volkov wave function describing the ionized electron laser-driven continuum dynamics disturbed by the Coulomb field of the ionic core. The SFA in different partitions of the total Hamiltonian is considered. The...

Source: http://arxiv.org/abs/1301.5764v1

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Sep 21, 2013
09/13

by
Petr Satunin

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We present an elementary derivation of the width of photon decay in a weak magnetic field using the semiclassical method of worldline instantons. The calculation is generalized to a model of quantum electrodynamics with broken Lorentz symmetry. Implications for the search of deviations from Lorentz invariance in the cosmic ray experiments are discussed.

Source: http://arxiv.org/abs/1301.5707v1

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Sep 21, 2013
09/13

by
Chad A. Husko; Sylvain Combrie; Pierre Colman; Jiangjun Zheng; Alfredo De Rossi; Chee Wei Wong

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Solitary waves have consistently captured the imagination of scientists, ranging from fundamental breakthroughs in spectroscopy and metrology enabled by supercontinuum light, to gap solitons for dispersionless slow-light, and discrete spatial solitons in lattices, amongst others. Recent progress in strong-field atomic physics include impressive demonstrations of attosecond pulses and high-harmonic generation via photoionization of free-electrons in gases at extreme intensities of 1014 Wcm2....

Source: http://arxiv.org/abs/1301.5748v1

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Sep 21, 2013
09/13

by
João Faria Martins; Roger Picken

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We define an invariant of tangles and framed tangles given a finite crossed module and a pair of functions, called a Reidemeister pair, satisfying natural properties. We give several examples of Reidemeister pairs derived from racks, quandles, rack and quandle cocycles, 2-crossed modules and braided crossed modules. We prove that our construction includes all rack and quandle cohomology (framed) link invariants, as well as the Eisermann invariant of knots, for which we also find a lifting by...

Source: http://arxiv.org/abs/1301.3803v2

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Sep 21, 2013
09/13

by
Ambroise Vest

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We prove the well-posedness of a linear closed-loop system with an explicit (already known) feedback leading to arbitrarily large decay rates. We define a mild solution of the closed-loop problem using a dual equation and we prove that the original operator perturbed by the feedback is (up to the use of an extension) the infinitesimal generator of a strongly continuous group. We also give a justification to the exponential decay of the solutions. Our method is direct and avoids the use of...

Source: http://arxiv.org/abs/1301.5744v1

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Sep 21, 2013
09/13

by
Dirk Lebiedz; Jochen Siehr

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Model reduction methods often aim at an identification of slow invariant manifolds in the state space of dynamical systems modeled by ordinary differential equations. We present a predictor corrector method for a fast solution of an optimization problem the solution of which is supposed to approximate points on slow invariant manifolds. The corrector method is either an interior point method or a generalized Gauss--Newton method. The predictor is an Euler prediction based on the parameter...

Source: http://arxiv.org/abs/1301.5815v1

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Sep 18, 2013
09/13

by
Yongjin Jiang; Tony Low; Kai Chang; Mikhai I. Katsnelson; Francisco Guinea

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The generation of valley current is a fundamental goal in graphene valleytronics but no practical ways of its realization are known yet. We propose a workable scheme for the generation of bulk valley current in a graphene mechanical resonator through adiabatic cyclic deformations of the strains and chemical potential in the suspended region. The accompanied strain gauge fields can break the spatial mirror symmetry of the problem within each of the two inequivalent valleys, leading to a fnite...

Source: http://arxiv.org/abs/1209.1770v2

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Sep 21, 2013
09/13

by
Aman G. Kidanemariam; Clemens Chan-Braun; Todor Doychev; Markus Uhlmann

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We have performed direct numerical simulation of turbulent open channel flow over a smooth horizontal wall in the presence of finite-size, heavy particles. The spherical particles have a diameter of approximately 7 wall units, a density of 1.7 times the fluid density and a solid volume fraction of 0.0005. The value of the Galileo number is set to 16.5, while the Shields parameter measures approximately 0.2. Under these conditions, the particles are predominantly located in the vicinity of the...

Source: http://arxiv.org/abs/1301.5771v1

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Sep 21, 2013
09/13

by
Diego Gonzalez; Merced Montesinos; Mercedes Velazquez

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The Plebanski formulation of complex general relativity is given in terms of variables valued in the complexification of the $so(3)$ Lie algebra. Therefore, it is genuinely a gauge theory that is also diffeomorphism-invariant. For this reason, the way that the Levi-Civita connection emerges from this formulation is not direct because both the internal (gauge) and the spacetime connections are geometrical structures a priori not related, there is not a natural link between them. Any possible...

Source: http://arxiv.org/abs/1204.4225v2

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Sep 21, 2013
09/13

by
Patrick Clarke; Rodrigo C. de Lamare

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This chapter presents joint interference suppression and power allocation algorithms for DS-CDMA and MIMO networks with multiple hops and amplify-and-forward and decode-and-forward (DF) protocols. A scheme for joint allocation of power levels across the relays and linear interference suppression is proposed. We also consider another strategy for joint interference suppression and relay selection that maximizes the diversity available in the system. Simulations show that the proposed cross-layer...

Source: http://arxiv.org/abs/1301.5912v1

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52

Sep 20, 2013
09/13

by
D. Pagel; A. Alvermann; H. Fehske

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We study the dissipative quantum harmonic oscillator with general non-thermal preparations of the harmonic oscillator bath. The focus is on equilibration of the oscillator in the long-time limit and the additional requirements for thermalization. Our study is based on the exact solution of the microscopic model obtained by means of operator equations of motion, which provides us with the time evolution of the central oscillator density matrix in terms of the propagating function. We find a...

Source: http://arxiv.org/abs/1205.2068v2

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23

Sep 21, 2013
09/13

by
Bhal Chandra Joshi

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In the last decade, the use of an ensemble of radio pulsars to constrain the characteristic strain caused by a stochastic gravitational wave background has advanced the cause of detection of very low frequency gravitational waves significantly. This electromagnetic means of gravitational wave detection, called Pulsar Timing Array(PTA), is reviewed in this article. The principle of operation of PTA, the current operating PTAs and their status is presented along-with a discussion of the main...

Source: http://arxiv.org/abs/1301.5730v1

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39

Sep 21, 2013
09/13

by
Satoshi Takabe; Koji Hukushima

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We study minimum vertex cover problems on random \alpha-uniform hypergraphs using two different approaches, a replica method in statistical mechanics of random systems and a leaf removal algorithm. It is found that there exists a phase transition at the critical average degree e/(\alpha-1). Below the critical degree, a replica symmetric ansatz in the statistical-mechanical method holdsand the algorithm estimates a solution of the problem which coincide with that by the replica method. In...

Source: http://arxiv.org/abs/1301.5769v1

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Sep 21, 2013
09/13

by
Aymeric Delteil; Angela Vasanelli; Yanko Todorov; Bruno Paulillo; Giorgio Biasiol; Lucia Sorba; Carlo Sirtori

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The optical response of a heavily doped quantum well, with two occupied subbands, has been investigated as a function of the electronic density. It is shown that the two optically active transitions are mutually coupled by dipole-dipole Coulomb interaction, which strongly renormalizes their absorption amplitude. In order to demonstrate this effect, we have measured a set of optical spectra on a device in which the electronic density can be tuned by the application of a gate voltage. Our results...

Source: http://arxiv.org/abs/1301.5837v1